Pediatric Orthopaedic Unit Department of Orthopaedic Surgery Pusan National University Hospital

1. Improvement of femoral head roundness after valgus femoral osteotomyin Legg-Calve-Perthes disease Hui Taek Kim, MD and Seong Ho Bae, MD Pediatric Orthopaedic Unit Department of Orthopaedic Surgery Pusan National University Hospital

2. Introduction • Deformation of the femoral head in Legg-Calve-Perthes disease (LCPD) • Latter in fragmentation or early in regeneration stage • Best time to perform surgery • Avascular necrosis and fragmentation stage

3. Introduction • Containment of the affected femoral head • Abduction brace • Soft tissue release and/or varus femoral osteotomy • Salter innominate osteotomy • The results are frequently poor • > 8 years old • Uncontained femoral head and hinge abduction

4. Introduction • Valgus femoral osteotomy (VFO) • Relieves hinge abduction • Provides better functional range of movement by rotating the less affected femoral head into weight bearing position

5. Purpose • To quantify the changes of femoral head roundness after valgus femoral osteotomy • Using new measuring method

6. Materials and Methods

7. Materials and Methods • 48 children • September 1997 to January 2006 • Group 1: non-operative Tx. (25 hips) • 21 hips in pillar B (19 > 8 yrs old) • 4 hips in pillar C (2 > 8 yrs old ) Group 2: treated by VFO (23 hips) • 7 hips in pillar B (3 > 8 yrs old) • 16 hips in pillar C (7 > 8 yrs old)

8. Materials and Methods • Overall patient age was 8.3 years • Group 1 : 8.7 years • Group 2 : 8.1 years Chiari OT : 10.2 years (3 cases) Triple innominate OT : 6.5 years (2 cases) • Male : 43 Female : 5 • Mean follow-up period : 6.4 years

9. Materials and Methods • Indications for VFO • Hip pain • Decreased range of motion • Hinge abduction on MRI and arthrography • Significant deformity of the femoral head • Open wedge type • Soft tissue release or shortening (×)

10. Materials and Methods • Femoral head roundness • Roundness of the lateral third (RLT) • Roundness of the medial third (RMT) • Maximal epiphyseal height in middle third (MEH) • Ratio of radii of curvature of the medial third over the lateral third (RML)

11. Materials and Methods • Radiograph and MRI were taken at the same time (fragmentationstage) • MRI enables the visualization of the cartilaginous femoral head

12. Materials and Methods Measuring methods

13. Materials and Methods • Most clear image • Entire proximal femur • Fragmentation stage in MRI / residual stage in AP radiograph • Image-analysis software • Adobe Photoshop • Microsoft Power Point

14. Materials and Methods • Drawing • Femoral shaft axis • Femoral neck axis • Femoral head waist • Radius of circle in lateral and medial third of femoral head (RLT and RMT) • Maximal epiphyseal height (MEH) in middle third

15. Materials and Methods • First step • Magnification • Medial aspect of the femoral head and calcar # Medial aspect of the femoral head and calcar are minimally affected during disease process

16. Materials and Methods • Second step • Femoral shaft and neck axis • The most superolateral and inferomedial point of femoral head • Base line a′ A’ a A

17. Materials and Methods • Third step • Divide the base line into thirds • Draw lines parallel to the femoral neck axis through 2 points b′ a′ A’ B’ ‖ ‖ b B ‖ ‖ ‖ ‖ a A

18. Materials and Methods • Final step • Best fitting circle passing a′(A′) and b′(B′) placing the center of circle to the median of the line connecting a′(A′) and b′(B′) ┐ ┐ b′ a′ A’ B’ b B a R r A RLT # Definition of circle : The set of all points in a plane whichare equidistant from a given point (center of circle)

19. Materials and Methods • The ratio of maximal epiphyseal height (MEH) to the waist of the femoral head • • Subchondral bone instead of articular cartilage (in MRI) b′ a′ A’ B’ b B W W a A MEH

20. Materials and Methods Differential coefficient is decreased as the point of contact moves toward middle portion in ellipse Maximal epiphyseal height represent more effectively the head growth or roundness in the middle third

21. Materials and Methods r – R r • Final data analysis • Relative change of RLT (%) = × 100 (%) ┐ ┐ b′ a′ A’ B’ b B a R r A RLT # Definition of circle : The set of all points in a plane whichare equidistant from a given point (center of circle)

22. Materials and Methods m – M m • Final data analysis • Relative change of MEH (%) = × 100 (%) b′ a′ A’ B’ b B W W a A MEH

23. Amount of collapse in lateral portion of deformed femoral head # RML = ROC in medial 1/3 / ROC in lateral 1/3 (Rm / RL) R r R’ r’ ROC in lateral third : r ROC in medial third : r’ The ratio of ROC (RML) : r’/r ROC in lateral third : R ROC in medial third : R’ The ratio of ROC (RML) : R’/R D. Nelson, M. Zenios, K. Ward et al, JBJS 2007 * ROC : Radius Of Circle

24. Materials and Methods • Final Stulberg classification

25. Results

26. Comparison of each value : p < 0.05 by paired t-test

27. Comparison of each value : p < 0.05 by paired t-test

28. 20 20 Comparison of each value : p < 0.05 by paired t-test

30. Results • Final Stulberg classifications p = 0.09 by Pearson chi-square test

31. Conclusions

32. Conclusions • Femoral head roundness was improved with ossification of the affected hip • More round femoral head can be expected in the lateral pillar B hips than pillar C

33. Conclusions • However, VFO performed in the fragmentation stage of lateral pillar C hips leads to greater improvement in femoral head roundness than does non-surgical treatment of lateral pillar B hips

34. Case 1 M/7+3 Group 1

36. RMT 5.02 1% 5.08

37. RLT 6.00 25% 8.04

38. MEH 1.78/4.76 6% 1.68/4.75

39. RML 5.02/6.00 = 0.84 0.21 5.08/8.04 = 0.63

40. Case 2 M/10+0 Group 2

42. RMT 5.30 9% 5.80

43. RLT 6.34 32% 9.29

44. MEH 2.10 17% 1.80

45. RML 5.30/6.34 = 0.84 0.22 5.80/9.29 = 0.62

46. Thank you for your attention !